Unlike most natural compounds, molecular oxygen in its 3xcexa3gxe2x88x92 ground state has triplet multiplicity but not singlet multiplicity. The lowest excited singlet state of O2, the 1xcex94g state, is a metastable species. Being 94 kJ molxe2x88x921 above the triplet ground state, O2(1xcex94g) singlet delta oxygen (SDO) is extremely chemically reactive, finding application in bleaching, disinfection and chemical processes. Predictions and experiments have demonstrated that SDO can be generated through laser or electrical excitation of ground state oxygen.
The internal-combustion engine-powered motor vehicle industry represents a market of over $1 trillion per year. There are major health-related issues that are leading to much more stringent regulations on the exhaust and noise emissions of these engines. Present technology falls short of achieving higher power densities with greater efficiencies and reduced exhaust emissions. The harshness (NVH) of current engines limits many applications, particularly in light duty cycles, where the engines operates much of the time at idle and low load.
It is believed that SDO may play an important role in low-temperature combustion. Diesel engine experiments and modeling have demonstrated that engine performance can be enhanced by heating the inlet air. Since heating the air is one way to increase SDO, this is indirect evidence of SDO""s benefits. Fuel additives that chemically produce SDO are also observed to improve diesel engine performance. Chemical kinetics modeling has shown that SDO generation by temperature may explain some of the otherwise unexplained phenomena observed in diesel engines (e.g., temperatures required for ignition, observed ignition time delays). Although SDO radiation is observed from combustion processes, the precise role of the SDO contribution is not well understood.
This invention broadly seeks to control the singlet delta energy levels of molecular oxygen (SDO) intake to enhance the performance of internal-combustion engines, diesel engines in particular. In the preferred embodiments, this control takes place just prior to, and in the initial stages of, fuel injection.
The SDO can be generated using different methods according to the invention, including thermal means, optical/laser energy, electrical/electromagnetic excitation, or a combination of these approaches. SDO may also be generated through reactions of a chemical fuel additive or a laser-excited chemical additive.
A system for improving the performance of an internal combustion engine according to the invention includes a source or energy operative to generate singlet delta oxygen (SDO) from molecular oxygen, and apparatus for mixing the SDO with fuel prior to, or during, combustion. In the preferred embodiment, the SDO is delivered with air through an air-intake port, and a laser is used in a multi-pass absorption cell.